Performing stunts, like flying -- being thrown in the air sometimes 15 feet or more off the ground -- can win trophies when done well. When done wrong, it can be devastating, as Chelsea's team learned firsthand on Aug. 26, 2004.

That's the day the assistant coach wanted Chelsea to try something new.

"He said 'Pop her up real high and then we'll catch you,'" Barrett explains. "She went up 15 feet in the air and came down on her head. She had a fractured skull, she had bleeding on the brain and after that she had a lot of memory problems. We would be walking through a store and she would all of the sudden start screaming and crying because she didn't know who we were anymore."

In the past decade, cheerleading has gone from sideline distraction to extreme sport, with higher stunts at a younger age and a bigger risk.

A recent study by the National Center for Catastrophic Sports Injury Research found, in the last 25 years, cheerleading accounted for more than half of 112 catastrophic injuries to female high school and college athletes, including three deaths. But that doesn't count girls like Lauren Chang, who was cheering for an out-of-school squad last spring when she was kicked in the chest and died.

"I think the state of cheerleading today is a national crisis," says cheer safety advocate Kimberly Archie.

"Lots of girls compete with injuries and they're trained to suck it up," she says.

At a gym in Memphis, high schoolers talked about broken bones like they were badges of honor.

Are the girls ever told to try a stunt and think that might be taking it too far?

"Yeah, but we try it anyways," cheerleader Jessica Stone says with a laugh. "Sure, this might break my neck, but let's go!

Krista Parks did break her neck five years ago while trying a new stunt. She has constant pain and memory problems, but she remembers this much: "I wanted to win -- bottom line," she says with a laugh. "That's how everyone is. It's pressure city -- everyone is there to win."

As athletic as it looks, at high schools and colleges in most states, cheerleading is more like the chess club -- it's considered an activity, not a sport. And often, there's no referee to blow the whistle on dangerous stunts.